Lens speed is the maximum

aperture In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image o ...

diameter, or minimum

f-number An f-number is a measure of the light-gathering ability of an optical system such as a camera lens. It is calculated by dividing the system's focal length by the diameter of the entrance pupil ("clear aperture").Smith, Warren ''Modern Optical ...

, of a

photographic lens A camera lens, photographic lens or photographic objective is an optical lens (optics), lens or assembly of lenses (compound lens) used in conjunction with a camera body and mechanism to Imaging, make images of objects either on photographic film ...

. A lens with a larger than average maximum aperture (that is, a smaller minimum f-number) is called a "fast lens" because it can achieve the same exposure as an average lens with a faster

shutter speed In photography, shutter speed or exposure time is the length of time that the film or digital sensor inside the camera is exposed to light (that is, when the camera's shutter (photography), shutter is open) when taking a photograph. The am ...

. Conversely, a smaller maximum aperture (larger minimum f-number) is "slow" because it delivers less light intensity and requires a slower (longer) shutter speed. A fast lens speed is desirable in taking pictures in dim light, for stability with long

telephoto A telephoto lens, also known as telelens, is a specific type of a long-focus lens used in photography and cinematography, in which the physical length of the lens is shorter than the focal length. This is achieved by incorporating a special lens ...

lenses, and for controlling

depth of field The depth of field (DOF) is the distance between the nearest and the farthest objects that are in acceptably sharp focus (optics), focus in an image captured with a camera. See also the closely related depth of focus. Factors affecting depth ...

and bokeh, especially in portrait photography, as well as for

sports photography Sports photography refers to the genre of photography that covers all types of sports. In the majority of cases, professional sports photography is a branch of ''photojournalism,'' while amateur sports photography, such as photos of childre ...

and

photojournalism Photojournalism is journalism that uses images to tell a news story. It usually only refers to still images, but can also refer to video used in broadcast journalism. Photojournalism is distinguished from other close branches of photography (such ...

. Lenses may also be referred to as being "faster" or "slower" than one another; so an 3.5 lens can be described as faster than an 5.6 despite 3.5 not generally being considered "fast" outright. What ''is'' considered fast largely depends on focal length, image diameter (i.e. format covered, such as APS, full frame, medium format), and in the case of zoom lenses, zoom factor.

Tradeoffs

Attaining maximum lens speed requires engineering tradeoffs, and as such, "

prime A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only ways ...

" (fixed focal length) lenses are generally faster than zoom lenses. With 35mm film cameras and full-frame digital cameras, the fastest lenses are typically in the " normal lens" range near 50mm; here, there are several relatively inexpensive high-quality fast lenses available. For example, the Canon EF 50mm 1.8 II or Nikon AF Nikkor 50mm 1.8D are very inexpensive, but quite fast and optically well-regarded. Old fast manual focus lenses, such as the Nikkor-S(C) or Nikkor AI-S 50mm 1.4, or Canon's FD and M39 counterparts, were historically produced abundantly, and are thus sold relatively inexpensively on the used lens market. Especially outside of the "normal" focal length, lens speed also tends to correlate with the price and/or quality of the lens. This is because lenses with larger maximum apertures require greater care with regard to design, precision of manufacture, special coatings and quality of glass. At wide apertures,

spherical aberration In optics, spherical aberration (SA) is a type of aberration found in optical systems that have elements with spherical surfaces. This phenomenon commonly affects lenses and curved mirrors, as these components are often shaped in a spherical ...

becomes more significant and must be corrected. Thus, faster

and wide-angle retrofocus designs tend to be much more expensive. A telecompressor, also known as a speed booster, may be used to increase the speed of a lens with a corresponding reduction to its focal length. For example, the Metabones 0.58x BMPCC speed booster may be combined with a 1.2 lens to produce 0.74.

Fast lenses

While the fastest lenses in general production in the 2010s were 1.2 or 1.4, the 2020s have seen several 0.95 lenses, see below. What is considered "fast" has evolved to lower f-numbers over the years, due to advances in lens design, optical manufacturing, quality of glass,

optical coating An optical coating is one or more thin-film optics, thin layers of material deposited on an optical component such as a lens (optics), lens, prism (optics), prism or mirror, which alters the way in which the optic reflection (physics), reflects a ...

s, and the move toward smaller imaging formats. For example, the

1911 Encyclopædia Britannica Events January * January 1 – A decade after federation, the Northern Territory and the Australian Capital Territory are added to the Commonwealth of Australia. * January 3 ** 1911 Kebin earthquake: An earthquake of 7.7 Mom ...

states that "... ensesare also sometimes classified according to their rapidity, as expressed by their effective apertures, into extra rapid, with apertures larger than 6; rapid, with apertures from 6 to 8; slow, with apertures less than 11" whilst today, 6 would be deemed at the rather slow end. For scale, note that 0.5, 0.7, 1.0, 1.4, and 2.0 are each 1 f-stop apart (2× as fast), as an f-stop corresponds to a factor of the

square root of 2 The square root of 2 (approximately 1.4142) is the positive real number that, when multiplied by itself or squared, equals the number 2. It may be written as \sqrt or 2^. It is an algebraic number, and therefore not a transcendental number. Te ...

, about 1.4. Thus around 1.0, a change of 0.1 corresponds to about 1/4 of an f-stop (by linear approximation): 1.0 is about 50% faster than 1.2, which is about 50% faster than 1.4. , Canon, Nikon, Pentax and Sony all make an autofocus 50mm 1.4 lens. These are not unusual lenses and are relatively inexpensive. As of 2023, Canon also makes autofocus 50mm and 85mm 1.2 lenses, while Nikon makes a manual focus 58mm 0.95 lens and autofocus 50 and 85mm 1.2 lenses; see Canon EF 50mm lenses and Canon EF 85mm lenses for details. Pentax makes a 50mm 1.4 lens and 55mm 1.4 lens for

APS-C Advanced Photo System type-C (APS-C) is an image sensor format approximately equivalent in size to the Advanced Photo System film negative in its C ("Classic") format, of 25.1×16.7 mm, an aspect ratio of 3:2 and Ø 30.15 mm field d ...

cameras; see

Pentax lenses Pentax lenses were first badged as Takumar. The Takumar branded lenses were well respected for their line of Super Takumar, which designated the high performance coating applied to the lens as well as the optical formulas used to make them. The ...

. Sony makes several 50mm 1.4 lenses as well as a 50mm 1.2. The maximum

exposure time In photography, shutter speed or exposure time is the length of time that the film or digital sensor inside the camera is exposed to light (that is, when the camera's shutter is open) when taking a photograph. The amount of light that rea ...

for hand-held photography can be increased with an

image stabilisation Image stabilization (IS) is a family of techniques that reduce blurring associated with the motion of a camera or other imaging device during exposure. Generally, it compensates for pan and tilt (angular movement, equivalent to yaw and pi ...

system. In 2014,

Panasonic is a Japanese multinational electronics manufacturer, headquartered in Kadoma, Osaka, Kadoma, Japan. It was founded in 1918 as in Fukushima-ku, Osaka, Fukushima by Kōnosuke Matsushita. The company was incorporated in 1935 and renamed and c ...

introduced the fastest lens with in-built stabilisation, the Leica Nocticron 42.5 mm f/1.2, which can even be operated with dual image stabilisation (Dual I.S.), provided that the camera body has an additional stabilising system at the image sensor. In the mid 1960s, there was something of a fad for fast lenses among the major manufacturers. In 1966, in response to the trend,

Carl Zeiss Carl Zeiss (; 11 September 1816 – 3 December 1888) was a German scientific instrument maker, optician and businessman. In 1846 he founded his workshop, which is still in business as Zeiss (company), Zeiss. Zeiss gathered a group of gifted p ...

displayed a prop lens christened the Super-Q-Gigantar 40mm 0.33 at

photokina Photokina is a trade fair held in Europe for the photographic and imaging industries. It is the world's largest such trade fair. The first Photokina was held in Cologne, Germany, in 1950, and since 1966 it has been held biennially in Septemb ...

. Made from various parts found around the factory (the lenses came from a darkroom condenser enlarger), the claimed speed and focal lengths were purely nominal and it wasn't usable for photography.

Maximum possible speed

Theoretically, the smallest f-number is 0 (or

numerical aperture In optics, the numerical aperture (NA) of an optical system is a dimensionless number that characterizes the range of angles over which the system can accept or emit light. By incorporating index of refraction in its definition, has the property ...

of 1), corresponding to a lens with an infinite

entrance pupil In an optical system, the entrance pupil is the optical image of the physical aperture stop, as 'seen' through the optical elements in front of the stop. The corresponding image of the aperture stop as seen through the optical elements behin ...

diameter. In practice, that cannot be reached due to mechanical constraints of the camera system (shutter clearance, mount diameter). Even for systems that can be designed without significant constraints on lens size and image plane distance (e.g. microscopy and

photolithography Photolithography (also known as optical lithography) is a process used in the manufacturing of integrated circuits. It involves using light to transfer a pattern onto a substrate, typically a silicon wafer. The process begins with a photosensiti ...

systems), the cost of going beyond a numerical aperture of 0.95 (f/0.164) is usually prohibitive. In SLR camera systems, typical mount diameters are in the range of 44–54 mm, with flange distances around 45 mm. This limits the maximum possible f-number to 1.0 to 1.2, with rather strong vignetting towards the edges of the image. Flange distances are significantly smaller for

rangefinder A rangefinder (also rangefinding telemeter, depending on the context) is a device used to Length measurement, measure distances to remote objects. Originally optical devices used in surveying, they soon found applications in other fields, suc ...

and mirrorless cameras (even below 20 mm), theoretically enabling designs down to something like f/0.7 or even faster. The chance of seeing such lenses designed for use with 35mm (" full-frame") cameras, digital or film, in practice will be slim, since their cost and weight are likely not competitive with respect to equivalent imaging solutions employing larger sensors.

List of ultrafast lenses

Some of the fastest camera lenses in production were as follows: Voigtlaender

* Cosina Voigtländer Super Nokton 29mm 0.8

Micro Four Thirds The is a standard released by Olympus Corporation, Olympus Imaging Corporation and Panasonic in 2008, for the design and development of mirrorless interchangeable lens digital cameras, camcorders and Camera lens, lenses. Camera bodies are availab ...

mount * Cosina Voigtländer Nokton 10.5mm, 17.5mm, 25mm, 42.5mm, 60mm 0.95 for Micro Four Thirds mount *Vantage One T1.0 Cine lenses from 17.5mm to 120mm (Super35mm Spherical Primes) *SLR Magic 25mm T/0.95 * SLR Magic 35mm T/0.95 * Laowa 18mm, 25mm, 33mm 0.95 (T1.0) For Super35mm Frame sensor * Laowa 28mm, 35mm, 45mm 0.95 (T1.0) For Full Frame sensor * Handevision Ibelux 40mm 0.85 (made for Micro Four Thirds and various APS camera mounts, including Sony E-Mount and Fujifilm X-Mount) * Fujinon 43mm 0.85 ( VRF43LMD ) * Leica Noctilux-M 50mm 0.95 ASPH (announced on September 15, 2008, then the fastest

aspherical lens An aspheric lens or asphere (often labeled ''ASPH'' on eye pieces) is a lens (optics), lens whose surface profiles are not portions of a sphere or Cylinder (geometry), cylinder. In photography, a camera lens, lens assembly that includes an aspheri ...

to have reached mass production; MSRP of £6290 or approximately US$10,000). * Zhongyi Mitakon 50mm and 35mm 0.95 in various optical versions and mounts, of which at least the 50mm for Leica M rangefinders has been found to in fact only be 1.06! * Nikon Noct-Nikkor Z 58mm 0.95 The following lenses are no longer in production : * American Optical 81mm 3.259" 0.38 Solid Schmidt Mirror lens (designed for aerial reconnaissance) * GOI CV 20mm 0.5 Mirror lens (2.9 mm image diameter, 1948; design and glass types used are well documented for anyone wanting to build thei
own
* Signal Corps Engineering 33mm 0.6 * GOI Iskra-3 72mm 0.65 Mirror lens * Fujinon-IDEAX 125mm 0.67 and/or 0.85 (X-ray lens, two speeds quoted on front ring) * Zeiss Planar 50mm 0.7 (Limited 10-copies production for the

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

space program, later used on 35mm movie cameras by

Stanley Kubrick Stanley Kubrick (; July 26, 1928 – March 7, 1999) was an American filmmaker and photographer. Widely considered one of the greatest filmmakers of all time, Stanley Kubrick filmography, his films were nearly all adaptations of novels or sho ...

for some candlelit scenes in ''

Barry Lyndon ''Barry Lyndon'' is a 1975 epic historical drama film written, directed, and produced by Stanley Kubrick, based on the 1844 novel '' The Luck of Barry Lyndon'' by William Makepeace Thackeray. Narrated by Michael Hordern, and starring Ryan O'N ...

'') * Tokyo Kogaku Similar 50mm 0.7 (8 elements in 4 groups, limited production in 1944 for Japanese Army. In 1951, another three were produced, two of which were used on a

South Pole The South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is the point in the Southern Hemisphere where the Earth's rotation, Earth's axis of rotation meets its surface. It is called the True South Pole to distinguish ...

expedition) * Kinoptik Lynxar 60mm 0.7 (Reproduction lens, usable but not optimised for photography) * Wray 64mm 0.71 (Reproduction lens, usable but not optimised for photography) * LOMO 60mm 0.75 (Reproduction lens, usable but not optimised for photography) * Aerojet Delft Rayxar 105mm 0.75 Full Frame aerial photography lens * Aerojet Delft Rayxar 150mm 0.75 Medium Format aerial photography lens * Aerojet Delft Rayxar 250mm 0.75 Large Format aerial photography lens * American Optical 43mm 1.715" 0.8 * JML Optical 64mm 0.85 * Leica Summar 75mm 0.85 Reproduction lens, not for photography. * Leica Leitz-IR 150mm 0.85 Reproduction lens, not for photography. * Farrand Super Farron 76mm 0.87 * Farrand Super Farron 150mm 0.87 Medium Format aerial photography lens *

Canon Canon or Canons may refer to: Arts and entertainment * Canon (fiction), the material accepted as officially written by an author or an ascribed author * Literary canon, an accepted body of works considered as high culture ** Western canon, th ...

50mm 0.95 (made as a rangefinder-coupled version with proprietary external bayonet for Canon 7 rangefinders, and an uncoupled C-mount "TV" version) * Kiev Рекорд-4 (Rekord-4) 52mm 0.9 (rangefinder lens, remained a prototype despite better resolution than the Canon 50mm0.95 rangefinder lens) *

Nikon (, ; ) is a Japanese optics and photographic equipment manufacturer. Nikon's products include cameras, camera lenses, binoculars, microscopes, ophthalmic lenses, measurement instruments, rifle scopes, spotting scopes, and equipment related to S ...

TV-Nikkor 35mm 0.9 (Fastest Nikon lens ever made; TV lens in M39 lens mount, 12.6 mm diameter image circle) * Noktor 50mm 0.95 (C-mount lens converted for mirrorless cameras; the actual C-mount lens is still being made as D.O. Industries Kowa Navitron, JML, Tarcus; Elgeet Navitar, SLRMagic Hyperprime, Senko, Yakumo; Goyo; Ernitec Super) * SLR Magic HyperPrime CINE and LM 50mm 0.92 T0.95 (rangefinder lens, Erwin Puts measured it to be T1.1
Noctilux 0.95/50
* Astro Berlin 52mm 0.95 (Super-35 Cine lens) * Leitz Perkin Elmer 4.5" 114mm 0.95 T1 (aerial photography lens, 40mm image diameter, 1967) * Pacific Optical 25mm 1.0 (Medium Format 150° Fish-eye lens, 55 mm image diameter; only 3 copies were ever made: for the Canadian Government for aurora borealis research in the late 60s/early 70s. One of these lenses was used in the production of the IMAX movie Solarmax, one is presumed lost; the cost per piece was estimated at 250,000 USD) * Leica Noctilux-M 50mm 1.0 (Leica M mount, 1976; discontinued and replaced 2008 with a new Noctilux, see above) * Canon EF 50mm 1.0 L USM (for Canon EOS autofocus SLRs, announced 1987, released 1989, discontinued 2009) *

Panavision Panavision Inc. is an American motion picture equipment company (law), company founded in 1954 specializing in cameras and photographic lens, lenses, based in Woodland Hills, Los Angeles, Woodland Hills, California. Formed by Robert Gottschalk a ...

50mm 1.0 (Super-35 cine lens) *

Nikkor Nikkor is the brand of lenses produced by Nikon Corporation, including camera lenses for the Nikon F-mount and more recently, for the Nikon Z line of mirrorless cameras. Nikko parent company brand, from which the Nikkor brand evolved. The ''N ...

-O 50mm 1.0 Prototype lens for Nikkor-S Rangefinder camera * Leica ELCAN 90mm 1.0 * Wild Heerbrugg Reconar 98mm 1.0 Medium Format aerial photography lens * Kollmorgen 153mm 1.0 * Zeiss UR 250mm 1.0 *

8.5–25.5mm 1.0 zoom lens (made 1975–1983 for the 310XL Super 8mm silent and sound camera series, the fastest zoom lens ever made for Super8, originally advertised as facilitating "shooting at candlelight" in combination with 160-ASA films.)Lossau, Jürgen (2003). ''The Complete Catalogue Of Movie Cameras'', Hamburg/Germany, atoll medien, p. 59, *

Baker-Nunn camera A Schmidt camera, also referred to as the Schmidt telescope, is a catadioptric Astrophotography, astrophotographic Optical telescope, telescope designed to provide wide Field of view, fields of view with limited Aberration in optical systems, abe ...

500mm 0.75 twelve used for tracking satellites Apart from those already mentioned, many very fast lenses exist in C-mount (as used by

16mm film 16 mm film is a historically popular and economical Film gauge, gauge of Photographic film, film. 16 mm refers to the width of the film (about inch); other common film gauges include 8 mm film, 8 mm and 35mm movie film, 35 mm. It ...

cameras,

CCTV Closed-circuit television (CCTV), also known as video surveillance, is the use of closed-circuit television cameras to transmit a signal to a specific place on a limited set of monitors. It differs from broadcast television in that the signa ...

, medical & scientific imaging systems), including: * Fujinon 50mm 0.7 *

'TV-16' 25mm 0.78 * Fujinon YV2.7x2.9LR4A-SA 2.9-8mm 0.95 * Apollo 25mm 0.85 * Computar 8mm 0.8 (6.4 x 4.8 mm image) * Ernitec 25mm 0.85 * Fujinon 25mm 0.85 * Tarcus 25mm 0.85 * Kern Switar 18mm 0.9 (built for NASA for the Apollo Moon landing) * Ampex 'LE610 Television Lens' 25mm 0.95 * Angénieux 25mm 0.95 Type 'M1' and 'M2' (M1 was the original, more common, consumer-grade product, while M2 was aimed at the professional cine market, with better correction for aberrations and distortions) * Angénieux 28mm 0.95 Type 'M1' and 'M2' (for 16mm film) * Angénieux 35mm 0.95 * Angénieux 50mm 0.95 Type 'M1' and 'M2' * AstroScope 25mm 0.95 * Avenir 25mm 0.95 * Century 'Nighthawk' 25mm 0.95 * Carl Meyer 25mm 0.95 * Cinetar 25mm 0.95 * Goyo Optical 17mm, 25mm, and 50mm 0.95 * JML 25mm and 50mm 0.95 * Navitar 25mm and 50mm 0.95 (see also above entry to the Noktor) * Navitron 25mm and 50mm 0.95 (see also above entry to the Noktor) * Schneider Kreuznach 'Xenon' 17mm, 25mm, and 50mm 0.95 * Senko 25mm and 50mm 0.95 (see also above entry to the Noktor) * Soligor 'Super Elitar' 25mm 0.95 * Som Berthiot 'Cinor' 25mm and 50mm 0.95 * Tarcus 'I.T.V. Lens' 50mm 0.95 * Precise Optics 50mm 0.95 * Kowa 50mm 0.95 * Yakumo 25mm and 50mm 0.95 * Zeika 'Nominar' 25mm 0.95 * Kaligar 'Nominar' 25mm 0.95 * Dallmeyer 25mm 0.99 (1930) * Astro Berlin 25mm 1.0 * Bausch & Lomb 29mm 1.0 * Astro Berlin 'Tachonar' 35mm and 75mm 1.0 * Carl Meyer Videostigmat 1.5" 38mm 1.0 * RTH (Rank/Taylor Hobson) Monital 130mm 1.0 made by SOPELEM in France, Super35mm cine lens Very fast lenses in D-mount for use in (Super-)8mm film and video (Hi)8 cameras: * Kern Switar 13mm 0.9 * Cinetor 'TELE-PHOTO' 37.5mm 1.0 * Walz 'TELEPHOTO' 37.5mm 1.0 * Amitar 'Telephoto' 38.1mm 1.0 * Rexer 'TELE' 38mm 1.0 * Manon 'Telephoto' 37.5mm 1.0 Very fast lenses used in X-ray machines: * Zeiss R-Biotar 100mm 0.73 * LOMO 100mm 0.73 *

50mm and 65mm 0.75 * Leitz 50mm and 65mm 0.75 * De Oude Delft Rayxar 50mm, 65mm and 105mm, and allegedly 150mm 0.75 * De Oude Delft Rayxar 90mm 1.0 * Astro-Berlin Tachon 65mm 0.75 * Rodenstock XR-Heligon 42mm and 50mm 0.75 * Rodenstock XR-Heligon 68mm f/1 * Kowa 42mm and 65mm 0.75 * Carl Zeiss Jena 50mm 0.77 * Kowa 55mm 0.8 * Zeiss R-Biotar 55mm 0.85 * Lenzar Optics 184.6mm 0.9 (Photographic lens made by Lenzar Optics Corp., Riviera Beach FL, 0.9–8) * Kowa 33.5mm 0.95 * Kowa 55mm 1.0 * Rodenstock Heligon 68mm 1.0 *

65mm and 90mm 1.0 * Fuji 90mm 1.0 * Kowa 90mm 1.0 * Zeiss R-Biotar 125mm 0.8

References

External links

Lenses: Fastest
Table of all fast lenses by focal length and image format covered.

f-number doesn't directly determine focal-plane illuminance, due to light transmission losses. * {{cbignore Science of photography